1. Field of the Invention
The present invention relates to a light source apparatus in which a plurality of light-emitting devices are aligned linearly, and which is employed as, for example, a backlight source of a small-sized liquid crystal display panel.
2. Background Art
A light source including a light guide plate and a linear light source apparatus (see, for example, Patent Document 1) provided on a side surface of the light guide plate has been known as a backlight source of the liquid crystal display panel of a cellular phone or a digital camera.
This linear light source apparatus includes an elongated rectangular printed board having thereon a wiring pattern; a plurality of light-emitting devices which are provided on the printed board so as to be separated from one another along a longitudinal direction of the printed board, and which are connected to the wiring pattern of the printed board; reflectors each having an inclined surface and which are provided on the two longitudinal sides of each light-emitting device; and a sealing resin portion which seals each of the light-emitting devices.
When the sealing resin portion of this linear light source apparatus is thermally cured, shrinkage occurs, and the light source apparatus warps so as to be convex downward (i.e., in a direction from the surface of the printed board on which the light-emitting devices are mounted toward the opposite surface of the printed board). Therefore, adhesion between the linear light source apparatus and the light guide plate is lowered, and the performance of light incidence to the light guide plate is reduced.
Patent Document 2 discloses a technique for preventing warpage of such a linear light source apparatus, in which a reflector corresponding to a light-emitting device and a reflector corresponding to another adjacent light-emitting device are discontinuously provided so as to be separated from each other by a groove formed therebetween. This groove relaxes stress caused by shrinkage of the sealing resin portion, and prevents warpage of the light source apparatus.
Patent Document 3 discloses a linear light source apparatus having a configuration similar to that of the linear light source apparatus disclosed in Patent Document 1, except that the reflectors are omitted, and a second substrate which is longer than each sealing resin portion in a longitudinal direction is provided on the bottom surface of the printed board (i.e., the surface opposite the surface on which the light-emitting devices are mounted) at a position corresponding to each light-emitting device such that each end of the second substrate is located between adjacent sealing resin portions. This patent document describes that torsion or warpage of the linear light source apparatus can be reduced by means of the second substrate.    Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2004-235139    Patent Document 2: Japanese Patent Application Laid-Open (kokai) No. 2006-120691    Patent Document 3: Japanese Patent Application Laid-Open (kokai) No. 2008-53571
However, the technique disclosed in Patent Document 2 may fail to exhibit a sufficient effect of preventing warpage of the light source apparatus. Therefore, there may arise problems in that adhesion between the light source apparatus and a light guide plate is lowered due to warpage of the apparatus; the performance of light incidence to the light guide plate is reduced; and the brightness of a backlight source is lowered. Even when the technique disclosed in Patent Document 3 is applied to the linear light source apparatus disclosed in Patent Document 2, warpage of the linear light source apparatus is not sufficiently suppressed.